The present invention relates to a cooling abnormality detection system for electronic equipment and, more particularly, to a cooling abnormality detection system for electronic equipment which prevents reliability degradation and breakdown of the electronic equipment due to heat.
In recent years, large scale integration and a higher packing density of circuit elements have progressed in electronic equipment such as computers to improve performance. Along with this trend, a heat generating density inside the equipment is increased, and the above electronic equipment frequently employ a cooling system using a liquid coolant. A typical conventional cooling system employs a flat plate through which a liquid coolant flows to cool the electronic equipment through this flat plate. In this system, a temperature sensor or an element having an equivalent function is arranged in an element or electronic equipment. An output from this sensor is monitored to prevent reliability degradation or breakdown of electronic elements and equipment due to heat.
FIG. 1 is a block diagram showing an arrangement of a conventional cooling abnormality detection system for cooling electronic equipment serving as a heating element by using the liquid coolant.
Referring to FIG. 1, reference numeral 11 denotes a cooling device; 12, a protection unit; 13, a heat exchanger for re-cooling the liquid coolant whose temperature is increased upon cooling of electronic components 43; 14, a tank for absorbing an increase/decrease in volume of the liquid coolant upon temperature change; 15, a pump for circulating the liquid coolant to electronic equipment 40; 16, an outlet port for supplying the liquid coolant to the electronic equipment 40; and 17, an inlet port for receiving the liquid coolant from the electronic equipment 40. The protection unit 12 sends a start or stop command to the heat exchanger 13 and the pump 15 through an operation command line 20. Reference numeral 23 denotes a flowmeter for measuring a flow rate of the liquid coolant during the operation of the pump. The flowmeter 23 informs the protection unit 12 of an abnormality through an abnormality detection line 25 when the actual flow rate is lower than a predetermined rate during the operation of the pump. Reference numeral 41 denotes an operation control unit for starting/stopping power supply to the electronic components 43; 18, a cooling piping for interconnecting the cooling device 11 and the electronic equipment 40; and 30, an abnormality signal line for signaling the abnormality of the cooling device 11 to the operation control unit 41. Reference numeral 42 denotes a temperature measuring unit for measuring temperatures of temperature sensors 44 (AD590 or AD592 available from Analog Devices Inc.) respectively arranged inside the electronic components 43; and 33, a temperature abnormality signal line for signaling a temperature abnormality from the temperature measuring unit 44 to the protection unit 12.
With the above arrangement, when the flowmeter 23 detects a decrease in a circulating flow rate of the liquid coolant, which disables continuous cooling in the cooling unit 11, the protection unit 12 drives the abnormality signal line 30 and sends an abnormality signal to the operation control unit 41. Thereafter, the operation control unit 41 stops power supply to the electronic components 43, thereby preventing reliability degradation and breakdown of the electronic components 43 due to heat.
When the temperature measuring unit 42 detects that power is not supplied to the electronic components 43 through power signal lines (not shown) under the control of the operation control unit 41, the temperature measuring unit 42 starts measuring temperatures of the temperature sensors 44. The temperature measuring unit 42 determines whether the measured temperatures exceed a predetermined temperature. The predetermined temperature is set to be a temperature which has almost no influence on the reliability of the electronic components 43.
When one of the temperatures of the electronic components 43 exceeds the predetermined temperature, the temperature measuring unit 42 determines an abnormality and informs the protection unit 12 of an abnormality through the temperature abnormality signal line 33. When the protection unit 12 receives the abnormality signal through the temperature abnormality signal line 33, it immediately informs the operation control unit 41 of an abnormality through the abnormality signal line 30. Thereafter, the operation control unit 41 stops power supply to the electronic components 43, thereby preventing reliability degradation and breakdown of the electronic components 43 due to heat.
In the above temperature abnormality detection, when the temperature measuring unit 42 determines that the measurement results exhibit high temperatures which exceed the highest rated temperature, the temperature measuring unit 42 informs the protection unit 12 of a "temperature sensor abnormality" through the temperature abnormality signal line 33. In a normal operation, a criterion for determining an abnormality of each temperature sensor 44 is set as a temperature higher by 20.degree. C. to 50.degree. C. than the predetermined temperature for determining the abnormality of the electronic components 43.
In this manner, when abnormality data from the flowmeter 23 or the temperature measuring unit 42 is signaled, the protection unit 12 informs the operation control unit 41 of an abnormality, and causes it to stop power supply to the electronic components 43, thereby preventing reliability degradation and breakdown of the electronic components 43 due to heat.
The conventional cooling abnormality detection system has the following drawbacks.
(1) When an abnormal flow rate of the liquid coolant is detected by the flowmeter, the protection unit stops power supply to the electronic components upon detection of an abnormal flow rate of the liquid coolant by the flowmeter. Therefore, even if a flow rate is normal, when a flow rate of the liquid coolant is decreased by an operation error or failure of the flowmeter, the protection unit determines an "abnormal flow rate". Then, the abnormality signal is sent to the operation control unit arranged inside the electronic equipment to stop power supply to the electronic components.
(2) When an abnormality of an electronic equipment is to be detected by the temperature sensors, power supply to the electronic components is stopped upon detection of an abnormal temperature of one of the electronic components. Therefore, even if the electronic component itself is normally cooled, an "abnormal temperature" is determined upon occurrence of an abnormality in one of the temperature sensors. Then, the abnormality signal is sent to the operation control unit inside the electronic equipment, and the power supply to the electronic components is undesirably interrupted.
(3) Drawback (2) can be solved when a determination reference for the "temperature sensor abnormality" is provided to determine the "temperature sensor abnormality" as described with reference to the prior art. However, even in this case, when the abnormal temperature sensor value input to the temperature measuring unit 42 falls within the range between the abnormal temperature predetermined value and the temperature sensor reference value, an abnormal temperature of an electronic component is detected as in drawback (2), thereby undesirably interrupting power supply to the electronic components.